K/T Boundary and
the Valles Caldera

Spring, 2000
May 14-18

Our trip to the K/T Boundary Impact Ejecta in the Raton Basin of Colorado & New Mexico was definitely a good one. Our usual fieldtrip leader, Jay couldn't make it, but Dave Kring led the trip. Our destination, which was carefully planned months in advance, was unfortunately in the grips of one of the worst forest fires that New Mexico had experienced in recent memory. So we had to do some last-minute alterations to the itinerary and camping spots.

Day 1

The first day was a driving day meant to get us from Tucson to northern NM, and the vehicles were prepped.

However, before finding a camping spot for the night, we did manage to stop at the Soda Dam across the Jemez River.
There, Paul talked about Travertine deposits and Rachel talked about life in hydrothermal environments.

Day 2
Our campsite had a great overlook of the Valles Caldera and Redondo Peak, a resurgent dome that Joe talked about.

We stopped at the La Cueva ash flows.

We also visited a locale where rhyolitic (Silica rich) ashflow and ashfall deposits were interbedded. The obsidian rich Banco Benito flow caps the formation.

Ingrid talked about Battleship Rock.

Day 3

We started the day off trying to get a good look at the Spanish Peaks, even though we weren't going to get that close to them.

We then headed to the only place that we were going to collect K/T samples. Dave knew where it was, but we spent some time trying to find it. You can see Terry up on the rocks looking for it. However, it ended up being way up above that.
Once Dave pointed it out to us, we sent some people down the slope to dig out a ledge for us.
The K/T Boundary layer itself looks like this.

Once we had our ledge, and had figured out what we were after, those that were interested, took some samples.

Although it may not look all that high or steep where we were, it was.

Day 4
Day 4 started with an early-morning flat tire.

Then we stopped at our first K/T outcrop of the day.

We were pretty sure that the large fault-bounded block was going to fall on Dave, so we just stayed away from that area and pointed at him.

The second outcrop that day was a little more of an uphill scramble, but the K/T layer there was a great exposure.

However, on the way down, people just kinda let gravity do the work. It was on this outcrop dismount that Peter almost killed himself by colliding with a gigantic rock.

When we got to camp that night, it was freezing. The vehicles pulled to a stop and everyone jumped out and started rummaging through their stuff for the warmest clothing. Additionally, the nearby forest fires made sunset especially colorful.

Day 5

Day five was a driving day as we headed back to Tucson. During our lunch stop, near some hills, we sudden look up, only to find that Erich as scaled to the top of a nearby hill, before most people could unfasten their seatbelts.

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Last Updated: 20 February 2001